Research and Application of Prefilled Concrete Wall to Reduce the Size of Stopping Mining Coal Pillar

Abstract

The long-term stability and width of stopping mining coal pillar have an important influence on mine safety production. In view of the “┤” type spatial structure of stop mining position of 6105 working face in Hongshuliang Coal Mine, the mechanical equilibrium, the distribution law of stress concentration factor, and the distribution characteristics of elastic zone of “filling body-remaining stopping mining “ structure are studied by means of theoretical calculation, FLAC3D numerical simulation software, and field measurement. The research shows that (1) the concrete filling body can protect the remaining stopping mining coal pillar, the surrounding rock of the retracement channel, and the surrounding rock of the main roadway, and the width formula of “ filling body - remaining stopping mining coal pillar “ structure is deduced; (2) in the retracement channel, increasing the internal friction angle and cohesion of coal can eliminate the spalling and large deformation of surrounding rock; (3) according to the comprehensive analysis, the width of the “filling body-remaining coal pillar” structure is 25 m, in which the width of the concrete filling body with uniaxial compressive strength of 50 MPa is 6 m, and the recovery rate of stopping mining coal pillar is increased by 52.5%; and (4) field measurement shows that in the retracement channel, there is no spalling and large deformation. In the auxiliary main haulage roadway, the maximum deformations of roof, floor, solid coal side, and stopping mining coal pillar side are 46 mm, 18.4 mm, 55.9 mm, and 74.8 mm, respectively.